XX.] THE MOVEMENTS OF THE EARTH. 351 



which she occupies on June 21, represented at No. i in the 

 figure. Here it is seen, that the incHnation of the axis 

 causes the north pole to be fully exposed to the sun ; and 

 the sun-lit half of the earth includes much more of the 

 northern, than of the southern, hemisphere. As the earth turns 

 round this sloping axis, the north pole and the surrounding 

 parts will continue in sunshine, during the entire rotation. 

 Within a circle measuring 23^° from the north pole, the sun 

 will not set ; and, within a similar circle around the south pole, 

 the sun will not rise. Anywhere, outside the polar regions, 

 there will be an alternation of day and night during the 24 

 hours; but the day, and night, will not be equal, except 

 at the equator. Thus, a place in the northern hemisphere, 

 like London, will have the day much longer than the 

 night ; for the figure shows that it will be kept, during 

 rotation, longer in sunshine than in shade. In fact, when 

 the earth is in this position, it is mtdsiivimer in the northern 

 hemisphere ; and, as the figure shows, it is iiiidwinter in 

 the southern hemisphere. These facts are more clearly 

 indicated in Fig. 113, which is an enlarged figure of the 

 earth in the same position as that of the small globe at 

 No. I in Fig. 112. 



As the earth travels round the sun, from June to Septem- 

 ber, it completes a quarter of its circuit. The days in the 

 northern hemisphere have been getting shorter, and the 

 nights longer ; and when the earth has reached the position 

 of No. 2 in Fig. 112, or on September 22, it is illuminated 

 as represented in Fig. 1 14.^ The boundary between the illumi- 

 nated and the shaded halves runs directly along a meridian, 



^ From the point of view from which this figure is supposed to be 

 taken, the inclination of the axis is not at first apparent. As the axis 

 always points in one direction, it cannot now incline towards the sun as 

 it did when in the position indicated in Fig. 113. In both figures, a 



